Ink composition

ABSTRACT

There is provided an ink composition, including: a combination of specific dyes, in which the dynamic contact angle of the ink to a silicon wafer is 24° or lower at 100 msec after dropping, and is 9° or lower at 5,100 msec after dropping.

BACKGROUND

1. Technical Field

The present invention relates to an ink composition.

2. Related Art

Ink jet recording methods can record high-definition images by arelatively simple apparatus, and have been rapidly developed in manyareas. Among these methods, various examinations for images of recordsto be obtained have been conducted. For example, for the purpose ofproviding a coloring composition having good fastness to ozone gas andhigh print density, JP-A-2013-122039 discloses a coloring compositioncontaining two kinds of predetermined phthalocyanine dyes.

An ink composition fills various ink containers, such as a cartridge, apack, and a large-capacity tank, and is then used. Thus, with theexpansion of ink usage, an ink composition excellent in high reliability(initial filling properties and (intermittent) printing stability) inaddition to light resistance is desired.

SUMMARY

An advantage of some aspects of the invention is to provide an inkcomposition excellent in initial filling properties and (intermittent)printing stability in addition to light resistance.

The present inventors have conducted intensive studies. As a result,they have found that the above problems can be solved by using apredetermined amount of a predetermined dye, thus completing theinvention.

That is, the invention is as follows.

[1] According to an aspect of the invention, there is provided an inkcomposition, including: a dye (Y-1) represented by a formula below; anda dye (Y-2) selected from the group consisting of C.I. Direct Yellows86, 132, and 142, in which the content ratio A of the dye (Y-1) and thedye (Y-2) (the dye (Y-1):the dye (Y-2)) is 7:3 to 9.5:0.5, the contentof the dye (Y-1) is 2.0 mass % to 5.0 mass %, and the dynamic contactangle of the composition to a silicon wafer is 24° or lower at 100 msecafter dropping, and is 9° or lower at 5,100 msec after dropping,

(in Formula (Y-1), R₄ represents a substituent, R₅ represents —OR₆ or—NHR₇, each of R₆ and R₇ represents a hydrogen atom or a substituent, X₃represents a divalent linking group, n0 is 0 or 1, Ar₃ represents adivalent heterocyclic group, and Ar₄ represents an alkyl group, an arylgroup, or a triazine group).

[2] In the ink composition according to [1], the content of the dye(Y-2) may be 0.10 mass % to 1.0 mass %.

[3] The ink composition according to [1] or [2] may include a dye (Y-3)represented by a formula below, in which the content of the dye (Y-3) is0.50 mass % to 1.5 mass %,

(in Formula (Y-3), R₁₃'s each independently represent a hydrogen atom ora substituent, R₁₄'s each independently represent —OR₁₆, —NHR₁₇, or acyano group, each of R₁₆ and R₁₇ represents a hydrogen atom or asubstituent, X₁ represents a substituted or unsubstituted aryl group ora substituted or unsubstituted triazine group, n6 is 0 or 1, Ar₁'s eachindependently represent a divalent heterocyclic group, and Ar₂'s eachindependently represent a substituted or unsubstituted alkyl group, asubstituted or unsubstituted aryl group, or a substituted orunsubstituted triazine group).

[4] The ink composition according to any one of [1] to [3] may include:an alkylene oxide adduct of an acetylene glycol having a main chain of12 or more carbon atoms; and an acetylene glycol having a main chain of10 or more carbon atoms.

[5] The ink composition according to any one of [1] to [4] may includepolyoxyalkylene alkyl ether.

[6] The ink composition according to any one of [1] to [5] may includetriethylene glycol alkyl ether.

[7] In the ink composition according to [6], the mass ratio of thetriethylene glycol alkyl ether to the polyoxyalkylene alkyl ether may be2 or more.

[8] In the ink composition according to any one of [5] to [7], thecontent of the polyoxyalkylene alkyl ether may be 1.0 mass % to 5.0 mass%.

[9] In the ink composition according to any one of [6] to [8], thecontent of the triethylene glycol alkyl ether may be 3.0 mass % to 15mass %.

[10] In the ink composition according to any one of [6] to [9], thetriethylene glycol alkyl ether may include triethylene glycol monobutylether.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, an embodiment of the invention (hereinafter, referred to as“present embodiment”) will be described in detail, but the invention isnot limited thereto. Various modifications can be made within the scopenot departing from the gist thereof.

Ink Composition

The ink composition according to the present embodiment includes: a dye(Y-1) represented by a formula below; and a dye (Y-2) selected from thegroup consisting of C.I. Direct Yellows 86, 132, and 142, in which thecontent ratio A of the dye (Y-1) and the dye (Y-2) (the dye (Y-1):thedye (Y-2)) is 7:3 to 9.5:0.5, the content of the dye (Y-1) is 2.0 mass %to 5.0 mass %, and the dynamic contact angle of the composition to asilicon wafer is 24° or lower at 100 msec after dropping, and is 9° orlower at 5,100 msec after dropping.

(In Formula (Y-1), R₄ represents a substituent, R₅ represents —OR₆ or—NHR₇, each of R₆ and R₇ represents a hydrogen atom or a substituent, X₃represents a divalent linking group, n0 is 0 or 1, Ar₃ represents adivalent heterocyclic group, and Ar₄ represents an alkyl group, an arylgroup, or a triazine group.)

Substituent Group A

First, substituent group A and ionic hydrophilic groups will be defined.

The substituent group A are not particularly limited, but examplesthereof include a halogen atom, an alkyl group, an aralkyl group, analkenyl group, an alkynyl group, an aryl group, a heterocyclic group, acyano group, a hydroxyl group, a nitro group, an alkoxy group, anaryloxy group, a silyloxy group, a heterocyclic oxy group, an acyloxygroup, a carbamoyloxy group, an alkoxycarbonyloxy group, anaryloxycarbonyloxy group, an amino group, an acylamino group, anaminocarbonylamino group, an alkoxycarbonylamino group, anaryloxycarbonylamino group, sulfamoylamino group, an alkyl or arylsulfonylamino group, a mercapto group, an alkylthio group, an arylthiogroup, a heterocyclic thio group, a sulfamoyl group, an alkyl or arylsulfinyl group, an alkyl or aryl sulfonyl group, an acyl group, anaryloxycarbonyl group, an alkoxycarbonyl group, a carbamoyl group, anaryl or heterocyclic azo group, an imide group, a phosphino group, aphosphinyl group, a phosphinyloxy group, a phosphinylamino group, asilyl group, a sulfonamide group, and an ionic hydrophilic group. Thesesubstituents may be further substituted. As the further substitutedsubstituent, a group selected from the above-described substituent groupA can be exemplified.

More specifically, examples of the halogen atom include a fluorine atom,a chlorine atom, a bromine atom, and an iodine atom.

As the alkyl group, a linear, branched, or cyclic substituted orunsubstituted alkyl group is exemplified. Examples of the alkyl groupinclude a cycloalkyl group, a bicycloalkyl group, and a tricyclostructure having many cyclic structures. Among the substituents to bedescribed below, an alkyl group (for example, an alkoxy group or analkyl group of an alkylthio group) also represents the alkyl group ofsuch a concept. Specifically, the alkyl group is preferably an alkylgroup having 1 to 30 carbon atoms, and examples thereof include a methylgroup, an ethyl group, an n-propyl group, an i-propyl group, a t-butylgroup, an n-octyl group, an eicosyl group, a 2-chloroethyl group, a2-cyanoethyl group, and a 2-ethylhexyl group. The cycloalkyl group ispreferably a substituted or unsubstituted cycloalkyl group having 3 to30 carbon atoms, and examples thereof include a cyclohexyl group, acyclopentyl group, and a 4-n-dodecyl cyclohexyl group. The bicycloalkylgroup is preferably a substituted or unsubstituted bicycloalkyl grouphaving 5 to 30 carbon atoms, that is, a monovalent group obtained byremoving one hydrogen atom from a bicycloalkane having 5 to 30 carbonatoms, and examples thereof include a bicyclo[1,2,2]heptan-2-yl groupand a bicyclo[2,2,2]octan-3-yl group.

As the aralkyl group, a substituted or unsubstituted aralkyl group isexemplified. The substituted or unsubstituted aralkyl group ispreferably an aralkyl group having 7 to 30 carbon atoms. Examplesthereof include a benzyl group and a 2-phenethyl group.

As the alkenyl group, a linear, branched, or cyclic substituted orunsubstituted alkenyl group is exemplified. Examples of the alkenylgroup include a cycloalkenyl group and a bicycloalkenyl group.Specifically, the alkenyl group is preferably a substituted orunsubstituted alkenyl group having 2 to 30 carbon atoms, and examplesthereof include a vinyl group, an allyl group, a prenyl group, a geranylgroup, and an oleyl group. The cycloalkenyl group is preferably asubstituted or unsubstituted cycloalkenyl having 3 to 30 carbon atoms,that is, a monovalent group obtained by removing one hydrogen atom froma cycloalkene having 3 to 30 carbon atoms, and examples thereof includea 2-cyclopenten-1-yl group and a 2-cyclohexen-1-yl group. Thebicycloalkenyl group is a substituted or unsubstituted bicycloalkenylgroup, and preferably a substituted or unsubstituted bicycloalkenylgroup having 5 to 30 carbon atoms, that is, a monovalent group obtainedby removing one hydrogen atom from a bicycloalkene having one doublebond, and examples thereof include a bicyclo[2,2,1]hept-2-en-1-yl groupand a bicyclo[2,2,2]oct-2-en-4-yl group.

The alkynyl group is preferably a substituted or unsubstituted alkynylgroup having 2 to 30 carbon atoms, and examples thereof include anethynyl group, a propargyl group, and a trimethylsilyl ethynyl group.

The aryl group is preferably a substituted or unsubstituted aryl grouphaving 6 to 30 carbon atoms, and examples thereof include a phenylgroup, a p-tolyl group, a naphthyl group, an m-chlorophenyl group, andan o-hexadecanoylaminophenyl group.

The heterocyclic group is preferably a monovalent group obtained byremoving one hydrogen atom from a 5- or 6-membered substituted orunsubstituted aromatic or non-aromatic heterocyclic compound, and morepreferably a 5- or 6-membered aromatic heterocyclic group having 3 to 30carbon atoms, and examples thereof include a 2-furyl group, a 2-thienylgroup, a 2-pyrimidinyl group, and a 2-benzothiazolyl group.

The alkoxy group is preferably a substituted or unsubstituted alkoxygroup having 1 to 30 carbon atoms, and examples thereof include amethoxy group, an ethoxy group, an isopropoxy group, a t-butoxy group,an n-octyloxy group, and a 2-methoxyethoxy group.

The aryloxy group is preferably a substituted or unsubstituted aryloxygroup having 6 to 30 carbon atoms, and examples thereof include aphenoxy group, a 2-methylphenoxy group, a 4-t-butylphenoxy group, a3-nitrophenoxy group, and a 2-tetradecanoylaminophenoxy group.

The silyloxy group is preferably a substituted or unsubstituted silyloxygroup having 0 to 20 carbon atoms, and examples thereof include atrimethylsilyloxy group and a diphenylmethylsilyloxy group.

The heterocyclic oxy group is preferably a substituted or unsubstitutedheterocyclic oxy group having 2 to 30 carbon atoms, and examples thereofinclude a 1-phenyltetrazole-5-oxy group and a 2-tetrahydropyranyloxygroup.

The acyloxy group is preferably a formyloxy group, a substituted orunsubstituted alkylcarbonyloxy group having 2 to 30 carbon atoms, or asubstituted or unsubstituted arylcarbonyloxy group having 6 to 30 carbonatoms, and examples thereof include an acetyloxy group, a pivaloyloxygroup, a stearoyloxy group, a benzoyloxy group, and a p-methoxyphenylcarbonyloxy group.

The carbamoyloxy group is preferably a substituted or unsubstitutedcarbamoyloxy group having 1 to 30 carbon atoms, and examples thereofinclude an N,N-dimethylcarbamoyloxy group, an N,N-diethylcarbamoyloxygroup, a morpholinocarbonyloxy group, an N, N-di-n-octylaminocarbonyloxygroup, and an N-n-octylcarbamoyloxy group.

The alkoxycarbonyloxy group is preferably a substituted or unsubstitutedalkoxycarbonyloxy group having 2 to 30 carbon atoms, and examplesthereof include a methoxycarbonyloxy group, an ethoxycarbonyloxy group,a t-butoxycarbonyloxy group, and an n-octylcarbonyloxy group.

The aryloxycarbonyloxy group is preferably a substituted orunsubstituted aryloxycarbonyloxy group having 7 to 30 carbon atoms, andexamples thereof include a phenoxycarbonyloxy group, ap-methoxyphenoxycarbonyloxy group, and ap-n-hexadecyloxyphenoxycarbonyloxy group.

The amino group is an alkylamino group, an arylamino group, or aheterocyclic amino group, and is preferably an amino group, asubstituted or unsubstituted alkylamino group having 1 to 30 carbonatoms, or a substituted or unsubstituted anilino group having 6 to 30carbon atoms, and examples thereof include a methylamino group, adimethylamino group, an anilino group, an N-methyl-anilino group, adiphenylamino group, and a triazinylamino group.

The acylamino group is preferably a formylamino group, a substituted orunsubstituted alkylcarbonylamino group having 1 to 30 carbon atoms, or asubstituted or unsubstituted arylcarbonylamino group having 6 to 30carbon atoms, and examples thereof include an acetylamino group, apivaloylamino group, a lauroylamino group, a benzoylamino group, and a3,4,5-tri-n-octyloxyphenylcarbonylamino group.

The amino carbonyl amino group is preferably a substituted orunsubstituted amino carbonyl amino group having 1 to 30 carbon atoms,and examples thereof include a carbamoyl amino group, anN,N-dimethylamino carbonyl amino group, an N,N-diethyl amino carbonylamino group, and a morpholino carbonyl amino group.

The alkoxycarbonylamino group is preferably a substituted orunsubstituted alkoxycarbonylamino group having 2 to 30 carbon atoms, andexamples thereof include a methoxycarbonylamino group, anethoxycarbonylamino group, a t-butoxycarbonylamino group, ann-octadecyloxycarbonylamino group, and an N-methyl-methoxycarbonylaminogroup.

The aryloxycarbonylamino group is preferably a substituted orunsubstituted aryloxycarbonylamino group having 7 to 30 carbon atoms,and examples thereof include a phenoxycarbonylamino group, ap-chlorophenoxycarbonylamino group, and anm-n-octyloxyphenoxycarbonylamino group.

The sulfamoylamino group is preferably a substituted or unsubstitutedsulfamoylamino group having 0 to 30 carbon atoms, and examples thereofinclude a sulfamoylamino group, an N,N-dimethylaminosulfonylamino group,and an N-n-octylaminosulfonylamino group.

The alkyl or aryl sulfonylamino group is preferably a substituted orunsubstituted alkyl sulfonylamino group having 1 to 30 carbon atoms or asubstituted or unsubstituted aryl sulfonylamino group having 6 to 30carbon atoms, and examples thereof include a methyl sulfonylamino group,a butyl sulfonylamino group, a phenyl sulfonylamino group, a2,3,5-trichlorophenyl sulfonylamino group, and a p-methylphenylsulfonylamino group.

The alkylthio group is preferably a substituted or unsubstitutedalkylthio group having 1 to 30 carbon atoms, and examples thereofinclude a methylthio group, an ethylthio group, and an n-hexadecylthiogroup.

The arylthio group is preferably a substituted or unsubstituted arylthiogroup having 6 to 30 carbon atoms, and examples thereof include aphenylthio group, a p-chlorophenylthio group, and an m-methoxyphenylthiogroup.

The heterocyclic thio group is preferably a substituted or unsubstitutedheterocyclic thio group having 2 to 30 carbon atoms, and examplesthereof include a 2-benzothiazolylthio group and a1-phenyltetrazole-5-ylthio group.

The sulfamoyl group is preferably a substituted or unsubstitutedsulfamoyl group having 0 to 30 carbon atoms, and examples thereofinclude an N-ethyl sulfamoyl group, an N-(3-dodecyloxypropyl)sulfamoylgroup, an N,N-dimethyl sulfamoyl group, an N-acetyl sulfamoyl group, anN-benzoyl sulfamoyl group, and an N—(N′-phenylcarbamoyl)sulfamoyl group.

The alkyl or aryl sulfinyl group is preferably a substituted orunsubstituted alkyl sulfinyl group having 1 to 30 carbon atoms or asubstituted or unsubstituted aryl sulfinyl group having 6 to 30 carbonatoms, and examples thereof include a methyl sulfinyl group, an ethylsulfinyl group, a phenyl sulfinyl group, and a p-methylphenyl sulfinylgroup.

The alkyl or aryl sulfonyl group is preferably a substituted orunsubstituted alkyl sulfonyl group having 1 to 30 carbon atoms or asubstituted or unsubstituted aryl sulfonyl group having 6 to 30 carbonatoms, and examples thereof include a methyl sulfonyl group, an ethylsulfonyl group, a phenyl sulfonyl group, and a p-methylphenyl sulfonylgroup.

The acyl group is preferably a formyl group, a substituted ornon-substituted alkyl carbonyl group having 2 to 30 carbon atoms, asubstituted or non-substituted aryl carbonyl group having 7 to 30 carbonatoms, or a substituted or unsubstituted heterocyclic carbonyl grouphaving 2 to 30 carbon atoms in which a carbonyl group is bonded to acarbon atom, and examples thereof include an acetyl group, a pivaloylgroup, a 2-chloroacetyl group, a stearoyl group, a benzoyl group, ap-n-octyloxyphenylcarbonyl group, a 2-pyridylcarbonyl group, and a2-furylcarbonyl group.

The aryloxycarbonyl group is preferably a substituted or unsubstitutedaryloxycarbonyl group having 7 to 30 carbon atoms, and examples thereofinclude a phenoxycarbonyl group, an o-chlorophenoxycarbonyl group, anm-nitrophenoxycarbonyl group, and a p-t-butylphenoxycarbonyl group.

The alkoxycarbonyl group is preferably a substituted or unsubstitutedalkoxycarbonyl group having 2 to 30 carbon atoms, and examples thereofinclude a methoxycarbonyl group, an ethoxycarbonyl group, at-butoxycarbonyl group, and an n-octadecyloxycarbonyl group.

The carbamoyl group is preferably a substituted or unsubstitutedcarbamoyl group having 1 to 30 carbon atoms, and examples thereofinclude a carbamoyl group, an N-methylcarbamoyl group, anN,N-dimethylcarbamoyl group, an N,N-di-n-octylcarbamoyl group, and anN-(methylsulfonyl) carbamoyl group.

The aryl or heterocyclic azo group is preferably a substituted orunsubstituted aryl azo group having 6 to 30 carbon atoms or asubstituted or unsubstituted heterocyclic azo group having 3 to 30carbon atoms, and examples thereof include a phenyl azo group, ap-chlorophenyl azo group, and a 5-ethylthio-1,3,4-thiadiazol-2-yl azogroup.

The imide group is preferably an N-succinimide group or an N-phthalimidegroup.

The phosphino group is preferably a substituted or unsubstitutedphosphino group having 0 to 30 carbon atoms, and examples thereofinclude a dimethyl phosphino group, a diphenyl phosphino group, and amethylphenoxy phosphino group.

The phosphinyl group is preferably a substituted or unsubstitutedphosphinyl group having 0 to 30 carbon atoms, and examples thereofinclude a phosphinyl group, a dioctyloxy phosphinyl group, and adiethoxy phosphinyl group.

The phosphinyloxy group is preferably a substituted or unsubstitutedphosphinyloxy group having 0 to 30 carbon atoms, and examples thereofinclude a diphenoxy phosphinyloxy group and a dioctyloxy phosphinyloxygroup.

The phosphinylamino group is preferably a substituted or unsubstitutedphosphinylamino group having 0 to 30 carbon atoms, and examples thereofinclude a dimethoxy phosphinylamino group and a dimethylaminophosphinylamino group.

The silyl group is preferably a substituted or unsubstituted silyl grouphaving 0 to 30 carbon atoms, and examples thereof include atrimethylsilyl group, a t-butyldimethylsilyl group, or aphenyldimethylsilyl group.

Ionic Hydrophilic Group

The ionic hydrophilic group is not particularly limited, but examplesthereof include a sulfo group, a carboxyl group, a thiocarboxyl group, asulfino group, a phosphono group, a dihydroxy phosphino group, and aquaternary ammonium group. Particularly, the ionic hydrophilic group ispreferably a sulfo group or a carboxyl group. Further, a carboxyl group,a phosphono group, and a sulfo group may be present in the form of asalt. Examples of the counter cation for forming the salt include anammonium ion, an alkali metal ion (for example, a lithium ion, a sodiumion, or a potassium ion), and an organic cation (for example, atetramethylammonium ion, a tetramethylguanidium ion, or atetramethylphosphonium ion). The salt is preferably a lithium salt, asodium salt, a potassium salt, or an ammonium salt, more preferably alithium salt or a mixed salt including the lithium salt as a maincomponent, and most preferably a lithium salt.

Color Material Represented by Formula (Y-1)

Hereinafter, an azo dye (yellow dye) represented by Formula (Y-1) willbe described in detail.

(in Formula (Y-1), R₄ represents a substituent, R₅ represents —OR₆ or—NHR₇, each of R₆ and R₇ represents a hydrogen atom or a substituent, X₃represents a divalent linking group, n0 is 0 or 1, Ar₃ represents adivalent heterocyclic group, and Ar₄ represents an alkyl group, an arylgroup, or a triazine group.).

In Formula (Y-1), the divalent heterocyclic group represented by Ar₃ ispreferably a 5- or 6-membered heterocyclic group, and may be furthercondensed. Further, the divalent heterocyclic group may be an aromaticheterocyclic ring or a non-aromatic heterocyclic ring. Examples of thedivalent heterocyclic group represented by Ar₃ include pyridine,pyrazine, pyrimidine, pyridazine, triazine, quinoline, isoquinoline,quinazoline, cinnoline, phthalazine, quinoxaline, pyrrole, indole,furan, benzofuran, thiophene, benzothiophene, pyrazole, imidazole,benzimidazole, triazole, oxazole, benzoxazole, thiazole, benzothiazole,isothiazole, benzisothiazole, thiadiazole, isoxazole, benzisoxazole,pyrrolidine, piperidine, piperazine, imidazolidine, and thiazoline.Among these, aromatic heterocyclic groups are preferable, and preferableexamples thereof, as exemplified above, include pyridine, pyrazine,pyrimidine, pyridazine, triazine, pyrazole, imidazole, benzimidazole,triazole, thiazole, benzothiazole, isothiazole, benzisothiazole, andthiadiazole. Thiadiazole is most preferable. They may further have asubstituent. Examples of the substituent are the same as theabove-mentioned substituent group A.

In Formula (Y-1), the substituent represented by R₄, R₆, and R₇ isselected from the above-mentioned substituent group A.

In Formula (Y-1), R₄ is preferably an alkyl group, an alkoxy group, oran aryl group, preferably an alkyl group having 1 to 4 carbon atoms,more preferably a methyl group, an ethyl group, a tertiary butyl group,a phenyl group, a methoxy group, or an ethoxy group, and furtherpreferably a tertiary butyl group.

In Formula (Y-1), R₅ is preferably a substituted or unsubstituted aminogroup, and more preferably an unsubstituted amino group.

In Formula (Y-1), Ar₄ is preferably a substituted or unsubstituted arylgroup, and more preferably a substituted or unsubstituted phenyl group.

In Formula (Y-1), when R₄, R₅, and Ar₄ further have a substituent,examples of the substituent include the above-mentioned substituentgroup A. Examples of the substituent include preferably an alkyl group,an aryl group, a heterocyclic group, a cyano group, a hydroxyl group, anitro group, or an alkoxy group, and more preferably an alkyl group, anaryl group, or a heterocyclic group.

In Formula (Y-1), examples of the divalent linking group represented byX₃ include preferably an alkylene group (for example, methylene,ethylene, propylene, butylene, or pentylene), an alkenylene group (forexample, ethenylene or propenylene), an alkynylene group (for example,ethynylene or propynylene), an arylene group (for example, phenylene ornaphthylene), a divalent heterocyclic group (for example, a6-chloro-1,3,5-triazine-2,4-diyl group, a pyrimidine-2,4-diyl group, ora quinoxaline-2,3-diyl group), —O—, —CO—, —NR_(A)— (R_(A) is a hydrogenatom, an alkyl group, or an aryl group), —S—, —SO₂—, —SO—, and acombination thereof.

In Formula (Y-1), the alkylene group, alkenylene group, alkynylenegroup, arylene group, or divalent heterocyclic group, represented by X3,and the alkyl group or aryl group represented by R_(A) may have asubstituent. Examples of the substituent are the same as those of theabove substituent. The alkyl group or aryl group represented by R_(A)includes a substituted or unsubstituted alkyl group or aryl group. Thesubstituted or unsubstituted alkyl group is preferably an alkyl grouphaving 1 to 30 carbon atoms, and the substituted or unsubstituted arylgroup is preferably an aryl group having 6 to 30 carbon atoms.

In Formula (Y-1), the divalent linking group represented by X₃ is morepreferably an alkylene group having 10 or less carbon atoms, analkenylene group having 10 or less carbon atoms, an alkynylene grouphaving 10 or less carbon atoms, an arylene group having 6 to 10 carbonatoms, a divalent heterocyclic group, —O—, —S—, or a combinationthereof, and further preferably an alkylene group, —S—, or a combinationthereof.

The total number of carbon atoms in the divalent linking group ispreferably 0 to 50, more preferably 0 to 30, and most preferably 0 to10.

In Formula (Y-1), the aryl group or arylene group represented by Ar₄ isthe same as the above-mentioned aryl group or arylene group representedby R_(A). Further, the triazine group represented by Ar₄ may have amonovalent substituent (the monovalent substituent is the same as thatin the above-mentioned substituent group A.).

The color material represented by Formula (Y-1) is not particularlylimited, but is preferably a compound represented by Formula (Y-1-1)below, and more preferably a compound represented by Formula (Y-1-2)below.

(in Formula (Y-1-1), R₄ represents a substituent, R₅ represents —OR₆ or—NHR₇, each of R₆ and R₇ represents a hydrogen atom or a substituent, X₃represents a divalent linking group, n0 is 0 or 1, Ar₃ represents adivalent heterocyclic group, A₁ represents an ionic hydrophilic group,and n1 represents 0 to 2.)

In Formula (Y-1-1), R₄, R₅, Ar₃, n0, and X₃ are the same as R₄, R₅, Ar₃,n0, and X₃ in Formula (Y-1).

In Formula (Y-1-1), the ionic hydrophilic group represented by A₁ ispreferably —SO₃M or —CO₂M, more preferably —SO₃M, and particularlypreferably —CO₂K. M's each independently represent a hydrogen atom or amonovalent counter cation. Examples of the monovalent counter cationinclude an ammonium ion, alkali metal ions (for example, lithium ion,sodium ion, and potassium ion), and organic cations (for example,tetramethyl ammonium ion, tetramethyl guanidium ion, and tetramethylphosphonium), preferably a lithium salt, a sodium salt, a potassiumsalt, and an ammonium salt, more preferably a potassium salt or a mixedsalt including the potassium salt as a main component, and mostpreferably a potassium salt.

Formula (Y-1-2):

(in Formula (Y-1-2), R₂₀ represents an alkylene group, —S—, or a linkinggroup including a combination thereof, R₂₁ represents an ionichydrophilic group, R₁₁ represents an alkyl group, and R₁₂ represents anamino group).

In Formula (Y-1-2), R₂₀ is the same as the alkylene group in thedivalent linking group represented by X₃ of Formula (Y-1).

In Formula (Y-1-2), R₂₁ represents a carboxyl group (—CO₂M). M's eachindependently represent a hydrogen atom or a monovalent counter cation.Examples of the monovalent counter cation include an ammonium ion,alkali metal ions (for example, lithium ion, sodium ion, and potassiumion), and organic cations (for example, tetramethyl ammonium ion,tetramethyl guanidium ion, and tetramethyl phosphonium), preferably alithium salt, a sodium salt, a potassium salt, and an ammonium salt,more preferably a potassium salt or a mixed salt including the potassiumsalt as a main component, and most preferably a potassium salt.

In the formula (Y-1-2), the alkyl group represented by R₁₁ and the aminogroup represented by R₁₂ are the same as the alkyl group and amino grouprespectively represented by R₄ and R₅ of Formula (Y-1).

Specific examples of the compound represented by Formula (Y-1) are shownbelow. However, the compound used in the present embodiment is notlimited to the following examples. Here, in specific examples, Et meansethyl, and Ph means phenyl.

pigment R 1 —SCH₂S— 2 —SCH₂CH₂S— 3 —SCH₂CH₂CH₂S— 4 —SCH₂CH₂CH₂CH₂CH₂S— 5

6

7 —SC₂H₄OC₂H₄S 8 —SC₂H₄OC₂H₄OC₂H₄S 9

10

11

12

13

14

15

16

17

pigment Ar R 18

—SC₃H₆S— 19

—SC₃H₆S— 20

—SC₃H₆S— 21

—SC₃H₆S— 22

—SC₃H₆S— 23

—SC₃H₆S—

pigment M 24 K 25 Li 26 NH₄ 27 NH(Et)₃

pigment R Ar 28 OEt

29 Ph

30 t-C₄H₉ C₃H₆SO₃Na

pigment R 31 —SCH₂CH₂S 32 —SCH₂CH₂CH₂S— 33 SCH₂CH₂CH₂CH₂CH₂S— 34

pigment R 35

36 NHC₂H₄COONa 37

The compound represented by Formula (Y-1) can be synthesized by ageneral synthesis method. For example, this compound can be synthesizedby the change of a diazo component and a coupling component or thevarious combinations thereof described in JP-A-2004-083903.

The content of the color material represented by Formula (Y-1) ispreferably 1.0 mass % to 7.0 mass %, more preferably 2.0 mass % to 6.0mass %, and further preferably 2.0 mass % to 5.0 mass %, with respect tothe total amount of yellow ink. When the content of the color materialrepresented by Formula (Y-1) is within the above range, there is atendency to obtain an image having excellent coloring ability, lightresistance, and color hue.

Dye (Y-2)

An example of the dye (Y-2) includes a dye selected from the groupconsisting of C.I. Direct Yellows 86, 132, and 142. In addition, the dye(Y-2) is not particularly limited, but examples thereof can include C.I.Direct Yellows 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, and 173.Among these, at least one of C.I. Direct Yellows 86 and 132 ispreferable. When such a dye is used, dye aggregation is relaxed in thehead nozzle face of an ink jet printer, and thus printing stabilitytends to be further improved.

The content of the dye (Y-2) is preferably 0.050 mass % to 1.2 mass %,more preferably 0.10 mass % to 1.0 mass %, and further preferably 0.30mass % to 0.90 mass %. When the content of the dye (Y-2) is 0.050 mass %or more, dye aggregation is relaxed in the head nozzle face of an inkjet printer, and thus printing stability tends to be further improved.Further, when the content of the dye (Y-2) is 1.2 mass % or less, dyeaggregation is relaxed in the head nozzle face of an ink jet printerwithout deteriorating the light resistance performance of printedmatter, which is the inherent nature of the dye (Y-1), and thus printingstability tends to be further improved.

The content ratio A of the dye (Y-1) and the dye (Y-2) (the dye(Y-1):the dye (Y-2)) is preferably 7:3 to 9.5:0.5, more preferably7.5:2.5 to 9.3:0.7, and further preferably 8:2 to 9:1. When the contentratio A is within the above range, dye aggregation is relaxed in thehead nozzle face of an ink jet printer without deteriorating the lightresistance performance of printed matter, which is inherent nature ofthe dye (Y-1), and thus printing stability tends to be further improved.

Compound Represented by Formula (Y-3)

The ink composition according to the present embodiment may furtherinclude a dye (Y-3) represented by Formula (Y-3). When the inkcomposition includes the dye (Y-3), the light resistance performance ofprinted matter tends to be further improved. Hereinafter, the dye (Y-3)represented by Formula (Y-3) will be described in detail.

(in Formula (Y-3), R₂₃'s each independently represent a hydrogen atom ora substituent, R₂₄'s each independently represent —OR₂₆, —NHR₂₇, or acyano group, each of R₁₆ and R₁₇ represents a hydrogen atom or asubstituent, X₁ represents a substituted or unsubstituted aryl group ora substituted or unsubstituted triazine group, n6 is 0 or 1, Ar₁'s eachindependently represent a divalent heterocyclic group, and Ar₂'s eachindependently represent a substituted or unsubstituted alkyl group, asubstituted or unsubstituted aryl group, or a substituted orunsubstituted triazine group.)

In Formula (Y-3), R₂₃'s are each independently preferably a hydrogenatom, a substituted or unsubstituted alkyl group, a substituted orunsubstituted alkoxy group, or a substituted or unsubstituted arylgroup, more preferably a hydrogen atom, a methyl group, an ethyl group,a tertiary butyl group, a phenyl group, a methoxy group, or an ethoxygroup, and further preferably a hydrogen atom or a tertiary butyl group.When each of R₂₃'s further has a substituent, examples of thesubstituent include the above-mentioned substituent group A. Thesubstituent is preferably an alkyl group, an aryl group, a heterocyclicgroup, a cyano group, a hydroxyl group, a nitro group, or an alkoxygroup, and more preferably an alkyl group, an aryl group, or aheterocyclic group.

Each of R₁₄'s is preferably a cyano group.

In Formula (Y-3), the divalent heterocyclic group represented by Ar_(t)is preferably a 5- or 6-membered heterocyclic group, and may have acondensed ring. Further, the divalent heterocyclic group may have anaromatic heterocyclic ring or a non-aromatic heterocyclic ring.

In Formula (Y-3), examples of the divalent heterocyclic grouprepresented by Ar_(t) include pyridine, pyrazine, pyrimidine,pyridazine, triazine, quinoline, isoquinoline, quinazoline, cinnoline,phthalazine, quinoxaline, pyrrole, indole, furan, benzofuran, thiophene,benzothiophene, pyrazole, imidazole, benzimidazole, triazole, oxazole,benzoxazole, thiazole, benzothiazole, isothiazole, benzisothiazole,thiadiazole, isoxazole, benzisoxazole, pyrrolidine, piperidine,piperazine, imidazolidine, and thiazoline. Among these, aromaticheterocyclic groups are preferable, and preferable examples thereof, asexemplified above, include pyridine, pyrazine, pyrimidine, pyridazine,triazine, pyrazole, imidazole, benzimidazole, triazole, thiazole,benzothiazole, isothiazole, benzisothiazole, and thiadiazole.Thiadiazole is most preferable. They may further have a substituent.Examples of the substituent are the same as the above-mentionedsubstituent group A. The substituent is preferably an alkyl group, anaryl group, a heterocyclic group, a cyano group, a hydroxyl group, anitro group, or an alkoxy group, and more preferably an alkyl group, anaryl group, or a heterocyclic group.

In Formula (Y-3), Ar₂'s are each independently preferably a substitutedor unsubstituted aryl group, further preferably a substituted orunsubstituted phenyl group, and particularly preferably a phenyl groupsubstituted with an ionic hydrophilic group. The ionic hydrophilic groupis preferably —SO₃M or —CO₂M, and more preferably —CO₂M. M's eachindependently represent a hydrogen atom or a monovalent counter cation.Examples of the monovalent counter cation include an ammonium ion,alkali metal ions (for example, lithium ion, sodium ion, and potassiumion), and organic cations (for example, tetramethyl ammonium ion,tetramethyl guanidium ion, and tetramethyl phosphonium), and preferablya lithium salt, a sodium salt, a potassium salt, and an ammonium salt.The ionic hydrophilic group is preferably a carboxyl group, and furtherpreferably a potassium salt of a carboxyl group.

In Formula (Y-3), the divalent linking group represented by X₁ ispreferably an alkylene group (for example, methylene, ethylene,propylene, butylene, or pentylene), an alkenylene group (for example,ethenylene or propenylene), an alkynylene group (for example, ethynyleneor propynylene), an arylene group (for example, phenylene ornaphthylene), a divalent heterocyclic group (for example, a6-chloro-1,3,5-triazine-2,4-diyl group, a pyrimidine-2,4-diyl group, ora quinoxaline-2,3-diyl group), —O—, —CO—, —NR_(A)— (R_(A) is a hydrogenatom, an alkyl group, or an aryl group), —S—, —SO₂—, —SO—, or acombination thereof. These groups may further be substituted with —OR₂₀(R₂₀ represents a hydrogen atom or a cation, and represents Li⁺ ion, Na⁺ion, K⁺ ion, or NH₄ ⁺ ion when M is a cation). The divalent linkinggroup is more preferably a divalent heterocyclic group, and particularlypreferably a 6-chloro-1,3,5-triazine-2,4-diyl group, and furtherparticularly preferably a 6-chloro-1,3,5-triazine-2,4-diyl groupsubstituted with —OR₂₀.

n6 is preferably 1.

The compound represented by Formula (Y-3) is preferably a compoundrepresented by Formula (Y-3-1) below, and further preferably a compoundrepresented by Formula (Y-3-2) below.

(in Formula (Y-3-1), R₂₃'s each independently represent a hydrogen atomor a substituent, R₁₄'s each independently represent —OR₁₆, —NHR₁₇, orcyano group, each of R₁₆ and R₁₇ represents a hydrogen atom or asubstituent, X₁ represents a substituted or unsubstituted aryl group ora substituted or unsubstituted triazine group, n0 is 0 or 1, Ar₁'s eachindependently represent a divalent heterocyclic group, A₄'s eachindependently represent an ionic hydrophilic group, and n7 represents 0to 2).

In Formula (Y-3-1), Ar₁, R₁₃, R₁₄, n6, and X₁ are the same as Ar₁, R₁₃,R₁₄, n6, and X₁ in Formula (Y-3).

In Formula (Y-3-1), the ionic hydrophilic group represented by A₄ ispreferably —SO₃M or —CO₂M, more preferably —SO₃M, and particularlypreferably —CO₂K. M's each independently represent a hydrogen atom or amonovalent counter cation. Examples of the monovalent counter cationinclude an ammonium ion, alkali metal ions (for example, lithium ion,sodium ion, and potassium ion), and organic cations (for example,tetramethyl ammonium ion, tetramethyl guanidium ion, and tetramethylphosphonium), preferably a lithium salt, a sodium salt, a potassiumsalt, and an ammonium salt, more preferably a potassium salt or a mixedsalt including the potassium salt as a main component, and mostpreferably a potassium salt.

In Formula (Y-3-1), n7 is preferably 1 or 2, and more preferably 2.

(In Formula (Y-3-2), R₁₅ represents —OM, R₂₀ represents —CO₂M, and Mrepresents a hydrogen atom or a monovalent counter cation. R₂₁represents a substituted or unsubstituted alkyl group, R₁₃'s eachindependently represent a hydrogen atom or a substituent, R₁₈ representsa substituted or unsubstituted amino group, and R₁₉ represents a cyanogroup.)

In Formula (Y-3-2), R₁₃ and M are the same as R₁₃ and M in Formula(Y-3).

In Formula (Y-3-2), R₂₁'s are each independently preferably a hydrogenatom, a substituted or unsubstituted alkyl group, a substituted orunsubstituted alkoxy group, or a substituted or unsubstituted arylgroup, more preferably a hydrogen atom, a methyl group, an ethyl group,a tertiary butyl group, a phenyl group, a methoxy group, or an ethoxygroup, and further preferably a hydrogen atom or a tertiary butyl group.When each of R₂₁'s further has a substituent, the substituent isexemplified in the above-mentioned substituent group A. The substituentis preferably an alkyl group, an aryl group, a heterocyclic group, acyano group, a hydroxyl group, a nitro group, or an alkoxy group, andmore preferably an alkyl group, an aryl group, or a heterocyclic group.

In Formula (Y-3-2), R₁₈ is preferably an unsubstituted amino group.

Next, specific examples of the compound represented by Formula (Y-3) areshown in Table below.

The above-mentioned compound is synthesized by the synthesis methoddescribed in JP-A-2006-57076 or JP-A-2007-217681.

The content of the dye represented by Formula (Y-3) is preferably 0.10mass % to 2.5 mass %, more preferably 0.25 mass % to 2.0 mass %, andfurther preferably 0.50 mass % to 1.5 mass %, with respect to the totalamount of the ink composition. When the content of the dye representedby Formula (Y-3) is within the above range, dye aggregation is relaxedin the head nozzle face of an ink jet printer, and thus there is atendency to further improve printing stability and obtain improved lightresistance performance of printed matter.

The content ratio B of the dye (Y-1) and the dye (Y-3) (the dye(Y-1):the dye (Y-3)) is preferably 65:35 to 95:5, more preferably 70:30to 90:10, and further preferably 75:25 to 85:15. When the content ratioB is within the above range, the light resistance performance of printedmatter tends to be further improved.

The content ratio C of (the dye (Y-2) and the dye (Y-3) the dye(Y-2):the dye (Y-3)) is preferably 15:85 to 65:35, more preferably 20:80to 60:40, and further preferably 25:75 to 55:45. When the content ratioC is within the above range, dye aggregation is relaxed in the headnozzle face of an ink jet printer, and thus printing stability tends tobe further improved.

Components Other than Dyes

Hereinafter, components other than dyes, which can be contained in theink composition, will be described. Alkylene oxide adduct of acetyleneglycol having a main chain of 12 or more carbon atoms and acetyleneglycol having a main chain of 10 or more carbon atoms

The ink composition according to the present embodiment preferablyincludes an alkylene oxide adduct of an acetylene glycol having a mainchain of 12 or more carbon atoms, and an acetylene glycol having a mainchain of 10 or more carbon atoms. When the ink composition includes thealkylene oxide adduct of an acetylene glycol, and the acetylene glycolhaving a main chain of 10 or more carbon atoms, color reproducibilityand bleeding are suppressed, and thus image quality tends to be furtherimproved. Alkylene oxide adduct of acetylene glycol having a main chainof 12 or more carbon atoms

The alkylene oxide adduct of an acetylene glycol having a main chain of12 or more carbon atoms (hereinafter, referred to as “acetylene glycolA”) is contained in an acetylene glycol-based surfactant (nonionicsurfactant) together with an acetylene glycol having a main chain of 10or more carbon atoms. The nonionic surfactant functions to uniformlyspread ink onto a recording medium. Therefore, when ink jet recording isperformed using the ink containing the nonionic surfactant, a relativelyhigh-resolution image with less bleeding can be obtained. Here, the“main chain” in the present specification means a main chain based onthe IUPAC nomenclature system.

In particular, since the acetylene glycol A has a main chain of 12 ormore carbon atoms, it has excellent wettability against a polymermember, such as rubber or plastic, constituting an ink flow channel, andforeign matter causing the generation of bubbles in the ink. Therefore,when the acetylene glycol A is used, it is possible to prevent thegenerated bubbles from remaining on the surface of the ink flow channelof the polymer member from an ink tank to a head. Further, in this case,initial filling properties are excellent, and both the growth ofresidual bubbles and the dead pixels caused by the detachment of bubblesattached to the surface of the ink flow channel can be prevented, so asto make continuous printing stability good. Moreover, since theacetylene glycol A is an alkylene oxide adduct, the solubility thereofin the ink is made excellent.

The hydrophlie-lipophile balance (HLB) value of the acetylene glycol Ais preferably 8 to 15 because the above-described wettability becomesfurther excellent. Here, the HLB value refers to a HLB value defined bythe Griffin method.

The acetylene glycol A is not particularly limited to below, butexamples thereof include compounds represented by Formula (1) below.

(In Formula (1), R¹, R^(1′), R², and R^(2′) each independently representan alkyl group having 1 to 5 carbon atoms, the number of carbon atoms inthe main chain is 12 or more, —OR³ Represents —OH or —O(C₂H₄O)_(m)H, and—OR^(3′) represents —OH or —O(C₂H₄O)_(n)H. In this case, m and n areeach independently a value including a decimal number of 0.5 to 25, andm+n is a value including a decimal number of 1 to 40 (however, exceptthe case that both —OR³ and —OR^(3′) are —OH).)

Specific examples of the acetylene glycol A include, but are not limitedto, ethoxylates of 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol andethoxylates of 5,8-dimethyl-6-dodecyne-5,8-diol. In the alkylene oxideadduct of acetylene glycol, an ethylene oxide adduct of acetylene glycoland a propylene oxide adduct of acetylene glycol are preferable, and anethylene oxide adduct of acetylene glycol is more preferable.

The addition number of moles of alkylene oxide units in acetylene glycolis preferably 1 mol to 20 mol with respect to each of R³ and R^(3′). Thetotal addition number of moles (sum of R³ and R^(3′)) is preferably 2mol to 40 mol. When the total addition number of moles of alkylene oxideis 40 mol or less, static and dynamic surface tension can be reduced,and thus the absorption performance of ink can be made good.

Examples of the commercially available product of the acetylene glycol Ainclude, but are not limited to, Olfine EXP4300 (trade name,manufactured by Nissin Chemical Industry Co., Ltd., carbon number 12,ethylene oxide adduct).

The acetylene glycol A may be used alone or in combination of two ormore kinds thereof.

The content of the acetylene glycol A contained in the ink compositionaccording to the present embodiment is preferably 0.050 mass % to 1.0mass %, more preferably 0.075 mass % to 0.75 mass %, and furtherpreferably 0.10 mass % to 0.50 mass %, with respect to the total amountof the ink composition. When the content of the acetylene glycol A is0.050 mass % or more, the wettability into a hydrophobic surfaceincreases, and thus filling properties tend to be further improved.Further, when the content of the acetylene glycol A is 0.30 mass % orless, dissolution stability tends to be further improved.

Acetylene Glycol Having a Main Chain of 10 or More Carbon Atoms

The acetylene glycol having a main chain of 10 or more carbon atoms(hereinafter, referred to as “acetylene glycol B”) can effectivelyremove the bubbles generated in the ink. Thus, initial fillingproperties and continuous printing stability are made excellent.

The HLB value of the acetylene glycol B is preferably 7 or less, andmore preferably 3 to 5 because of excellent defoaming properties.

The acetylene glycol B is not particularly limited to below, butexamples thereof include acetylene glycols represented by Formula (2)below.

(In Formula (2), R₁, R^(1′), R², and R^(2′) each independently representan alkyl group having 1 to 5 carbon atoms, the number of carbon atoms inthe main chain is 10 or more. Here, R¹, R^(1′), R², and R^(2′) inFormula (2) are not related to R¹, R^(1′), R², and R^(2′) in Formula (1)described above.)

Specific examples of the acetylene glycol B include, but are not limitedto, preferably 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol,5,8-dimethyl-6-dodecyne-5,8-diol, 2,4,7,9-tetramethyl-5-decyne-4,7-dioland 4,7-dimethyl-5-decyne-4,7-diol.

Examples of the commercially available product of the acetylene glycol Binclude, but are not limited to, Surfynol 104PG50(2,4,7,9-tetramethyl-5-decyne-4,7-diol), Surfynol DF110D(2,5,8,11-tetramethyl-6-dodecyne-5,8-diol) (all are trade names,manufactured by Air Products and Chemicals, Inc.).

The acetylene glycol B may be used alone or in combination of two ormore kinds thereof.

The content of the acetylene glycol B is preferably 0.050 mass % to 1.0mass %, more preferably 0.075 mass % to 0.75 mass %, and furtherpreferably 0.10 mass % to 0.50 mass %, with respect to the total amountof the ink composition. When the content of the acetylene glycol B is0.050 mass % or more, defoaming properties increase, and thus fillingproperties tend to be further improved. Further, when the content of theacetylene glycol B is 0.30 mass % or less, dissolution stability tendsto be further improved.

The total content of the acetylene glycol A and the acetylene glycol Bis preferably 0.10 mass % to 1.25 mass %, more preferably 0.30 mass % to1.0 mass %, and further preferably 0.45 mass % to 0.75 mass %, withrespect to the total amount of the ink composition. When the totalcontent of the acetylene glycol A and the acetylene glycol B is withinthe above range, solubility in ink is improved, and thus it is possibleto effectively prevent the generation of aggregate at the time ofblending these acetylene glycols.

Polyoxyalkylene Alkyl Ether

The ink composition according to the present embodiment may containpolyoxyalkylene alkyl ether. When the ink composition contains thepolyoxyalkylene alkyl ether, the solubility and dispersibility of theacetylene glycol A and the acetylene glycol B tend to be furtherimproved. Further, the polyoxyalkylene alkyl ether hardly affects thelow dynamic surface tension of the acetylene glycol A and the acetyleneglycol B.

Meanwhile, since an ink flow channel and an ink tank, each of which ismade of a hydrophobic material, are generally used in a continuous inksupply system (CISS), in the ink set used in the continuous ink supplysystem, it is effective for each ink to use a relatively hydrophobicsurfactant. From this viewpoint, it is effective to use the acetyleneglycol A and the acetylene glycol B in combination thereof. However,from the viewpoint of improving dissolution stability, initial fillingproperties and continuous printing stability while obtaining the effectsof the acetylene glycol A and the acetylene glycol B, particularly, whenthe ink set according to the present embodiment is used in a recordingapparatus provided with the continuous ink supply system (CISS), it ispreferable that each ink contains the polyoxyalkylene alkyl ether.

Here, the “ink supply system” refers to an ink supply system including:an ink storage container (ink tank) having an air inlet; a print headhaving nozzles for ejecting the liquid in the ink storage container; andan ink supply channel connecting the ink storage container and the printhead to supply the liquid from the ink storage container to the printhead.

Further, the “ink flow channel” refers to a flow channel for circulatingthe ink in an ink jet recording apparatus. Examples of the ink flowchannel include an ink supply channel for supplying the ink from the inkstorage container storing the ink to an ink jet type recording head anda flow channel for circulating the ink to the nozzle opening in the inkjet type recording head.

The HLB value of the polyoxyalkylene alkyl ether is preferably 11 to 16,and more preferably 12 to 15. When the HLB value of the polyoxyalkylenealkyl ether is within the above range, initial filling properties andcontinuous printing stability tend to be further improved.

Examples of the polyoxyalkylene alkyl ether include, but are not limitedto, compounds represented by Formula (3) below. When suchpolyoxyalkylene alkyl ether is used, storage stability and continuousprinting stability tend to be further improved.

R⁶O(C₂H₄O)_(w)(C₃H₆O)_(x)(C₂H₄O)_(y)(O₃H₆O)_(z)H  (3)

(In Formula (3), R⁶ represents an alkyl group having 1 to 20 carbonatoms, preferably an alkyl group having 5 to 15 carbon atoms, and morepreferably an alkyl group having 10 to 15 carbon atoms. w is a value of1 to 20, and x, y, and z are each independently a value of 0 or 1 to 20.w, x, y, and z satisfy 5≦w+x+y+z≦30, and preferably 5≦w+x+y+z≦25.)

Specific examples of the polyoxyalkylene alkyl ether include, but arenot limited to, C₁₂H₂₅O (C₂H₄O)₆ (C₃H₆O)₂ (C₂H₄O)₆ (C₃H₆O)₈H, C₁₃H₂₇O(C₂H₄O)₆(C₃H₆O)₂ (C₂H₄O)₆ (C₃H₆O)₈H, C₁₂H₂₅O (C₂F₁₄O)_(w) (C₃H₆O)_(x)(C₂H₄O)_(y)(C₃H₆O)_(z)H (here, w+y=15, x+z=4), C₁₃H₂₇O (C₂H₄O)_(w)(C₃H₆O)_(x) (C₂H₄O)_(y) (C₃H₆O)_(z)H (here, w+y=15, x+z=4), C₁₂H₂₅O(C₂H₄O)₈ (C₃H₆O)₂ (C₂H₄O)₆H, C₁₃H₂₇O (C₂H₄O)₈ (C₃H₆O)₂ (C₂H₄O)₆H,C₁₂H₂₅O (C₂H₄O)₁₂ (C₃H₆O)₂ (C₂H₄O)₁₂H, C₁₃H₂₇O (C₂H₄O)₁₂ (C₃H₆O)₂(C₂H₄O)₁₂H, CH₃ (CH₂)₉ (CH₃) CHO (C₂H₄O)₇ (C₃H₆O)_(4.5)H, CH₃ (CH₂)₁₁(CH₃) CHO (C₂H₄O)₇ (C₃H₆O)_(4.5)H, CH₃ (CH₂)₉ (CH₃) CHO (C₂H₄O)₅(C₃H₆O)_(3.5)H, CH₃ (CH₂)₁₁ (CH₃) CHO (C₂H₄O)₅ (C₃H₆O)_(3.5)H, C₁₄H₂₉O(C₂H₄O)₁₄ (C₃H₆O)₂H, C₁₁H₂₃O (C₂H₄O)₈H, C₁₀H₂₁O (C₂H₄O)₁₁H, andC₁₂H₂₅O(C₂H₄O)₁₅H.

Specific examples of the commercially available product of thepolyoxyalkylene alkyl ether include, but are not limited to, NOIGENDL-0415 (R⁶O(C₂H₄O)_(W)(C₃H₆O)_(x) (C₂H₄O)_(y) (C₃H₆O)_(z)H, “R⁶”: alkylhaving 12 or 13 carbon atoms, w+y=15, x+z=4, HLB value: 15.0), NOIGENET-116B (R⁶O (C₂H₄O)₇(C₃H₆O)_(4.5)H, “R⁶”: alkyl having 12 or 14 carbonatoms, HLB value: 12.0), NOIGEN ET-106A (R⁶O(C₂H₄O)₅(C₃H₆O)_(3.5)H,“R⁶”: alkyl having 12 or 14 carbon atoms, HLB value: 10.9), NOIGENDH-0300 (R⁶O(C₂H₄O)₂H, “R⁶”: alkyl having 14 carbon atoms, HLB value:4.0), NOIGEN YX-400 (R⁶O(C₂H₄O)₄₀H, “R⁶”: alkyl having 12 carbon atoms,HLB value: 18.1), NOIGEN EA-160 (C₉H₁₉C₆H₄O(C₂H₄O)_(16.8)H, HLB value:15.4) (all are manufactured by DKS Co. Ltd.), and EMULGEN 1108 (tradename, manufactured by Kao Corporation, R⁶O(C₂H₄O)₈H, “R⁶”: alkyl having11 carbon atoms, HLB value: 13.4).

The polyoxyalkylene alkyl ether may be used alone or in combination oftwo or more kinds thereof.

The content of the polyoxyalkylene alkyl ether is preferably 0.50 mass %to 5.50 mass %, more preferably 1.0 mass % to 5.0 mass %, and furtherpreferably 1.50 mass % to 4.50 mass %, with respect to the total amountof the ink composition. When the content of the polyoxyalkylene alkylether is within the above range, storage stability and continuousprinting stability tend to be further improved.

The content of the polyoxyalkylene alkyl ether is preferably 5.0 partsby mass to 15 parts by mass, and more preferably 7.5 parts by mass to12.5 parts by mass, with respect to 1 part by mass of the content of theacetylene glycol A. When the content of the polyoxyalkylene alkyl etheris within the above range, the acetylene glycol A is sufficientlysolubilized, and thus water solubility tends to be improved. Therefore,there is a tendency to prevent the generation of aggregates at the timeof blending or the occurrence of variation in absorptivity of ink.

The content of the polyoxyalkylene alkyl ether is preferably 2.5 partsby mass to 7.5 parts by mass, and more preferably 3.5 parts by mass to6.5 parts by mass, with respect to 1 part by mass of the total contentof the acetylene glycol A and the acetylene glycol B. When the contentof the polyoxyalkylene alkyl ether is within the above range, theacetylene glycol A and the acetylene glycol B are sufficientlysolubilized, and thus water solubility is improved. Therefore, there isa tendency to prevent the generation of aggregates at the time ofblending the polyoxyalkylene alkyl ether with the acetylene glycol A andthe acetylene glycol B or the occurrence of variation in absorptivity ofink.

Other Surfactants

The ink composition according to the present embodiment may contain asurfactant other than the above-described surfactant. The surfactant isnot particularly limited, but preferable examples thereof include atleast one of a fluorine-based surfactant and a silicone-basedsurfactant. When ink contains these surfactants, the dryness of the inkadhered to a cloth becomes better, and high-speed printing can beperformed.

Among these surfactant, a silicone-based surfactant is more preferablebecause the solubility in the ink becomes high and foreign matter ishardly generated in the ink.

The fluorine-based surfactant is not particularly limited, but examplesthereof include perfluoroalkyl sulfonates, perfluoroalkyl carboxylates,perfluoroalkyl phosphate esters, perfluoroalkyl ethylene oxide adducts,perfluoroalkyl betaine, and perfluoroalkyl amine oxide compounds. Thecommercially available product of the fluorine-based surfactant is notparticularly limited, but examples thereof include S-144 and S-145(manufactured by Asahi Glass Co., Ltd.); FC-170C, FC-430, andFLUORAD-FC4430 (manufactured by Sumitomo 3M Co., Ltd.); FSO, FSO-100,FSN, FSN-100, and FS-300 (manufactured by DUPONT COMPANY LIMITED); andFT-250 and FT-251 (manufactured by NEOS COMPANY LIMITED). Thesefluorine-based surfactants may be used alone or in combination of two ormore kinds thereof.

Examples of the silicone-based surfactant include polysiloxane-basedcompounds and polyether-modified organosiloxane. The commerciallyavailable product of the silicone-based surfactant is not particularlylimited, but specific examples thereof include BYK-306, BYK-307,BYK-333, BYK-341, BYK-345, BYK-346, BYK-347, BYK-348, and BYK-349 (allare trade names, manufactured by BYK Japan KK), and KF-351A, KF-352A,KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643,KF-6020, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (all aretrade names, manufactured by Shin-Etsu Chemical Co., Ltd.).

Solvent

The ink composition may further contain a solvent. The solvent is notparticularly limited, but examples thereof include an organic solventand water.

Examples of the water include pure water, such as ion exchange water,ultrafiltration water, reverse osmosis water, and distilled water; andwater for removing ionic impurities as much as possible, such asultrapure water. When water sterilized by ultraviolet irradiation or bythe addition of hydrogen peroxide, it is possible to prevent thegeneration of mold or bacteria in the case of long-term storage of ink.Thus, storage stability tends to be further improved.

Among the organic solvents, a volatile water-soluble organic solvent ismore preferable. The organic solvent is not particularly limited, butspecific examples thereof include alcohols or glycols, such as glycerin,ethylene glycol, diethylene glycol, triethylene glycol, propyleneglycol, dipropylene glycol, 1,3-propanediol, 1,2-butanediol,1,2-pentanediol, 1,2-hexanediol, 1,4-butanediol, 1,5-pentanediol,1,6-hexanediol, diethylene glycol mono-n-propyl ether, ethylene glycolmono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethyleneglycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether,diethylene glycol mono-n-butyl ether, triethylene glycol monobutylether, diethylene glycol mono-t-butyl ether, propylene glycol monomethylether, propylene glycol monoethyl ether, propylene glycol mono-t-butylether, propylene glycol mono-n-propyl ether, propylene glycolmono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropyleneglycol mono-n-butyl ether, dipropylene glycol mono-n-propyl ether,dipropylene glycol mono-iso-propyl ether, diethylene glycol dimethylether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether,diethylene glycol ethyl methyl ether, diethylene glycol butyl methylether, triethylene glycol dimethyl ether, tetraethylene glycol dimethylether, dipropylene glycol dimethyl ether, dipropylene glycol diethylether, tripropylene glycol dimethyl ether, methanol, ethanol, n-propylalcohol, iso-propyl alcohol, n-butanol, 2-butanol, tert-butanol,iso-butanol, n-pentanol, 2-pentanol, 3-pentanol, and tert-pentanol;N,N-dimethylformamide; N,N-dimethylacetamide; 2-pyrrolidone;N-methyl-2-pyrrolidone; 2-oxazolidone; 1,3-dimethyl-2-imidazolidinone;dimethyl sulfoxide; sulfolane; and 1,1,3,3-tetramethylurea.

These solvents may be used alone or in combination of two or more kindsthereof. The content of the organic solvent is not particularly limited,and, if necessary, can be appropriately determined. From the viewpointof improvement in compatibility with the polyoxyethylene alkyl ether,triethylene glycol alkyl ethers such as triethylene glycol monobutylether are preferable.

The content of triethylene glycol alkyl ether is preferably 3.0 mass %to 15 mass %, more preferably 3.0 mass % to 12.5 mass %, and furtherpreferably 3.0 mass % to 10 mass %. When the content of triethyleneglycol alkyl ether is within the above range, in the ink jet headnozzles, the ejection defect caused by the separation of the surfactanttends to be further suppressed.

The mass ratio of triethylene glycol alkyl ether to polyoxyalkylenealkyl ether is preferably 1.5 or more, more preferably 1.75 or more, andfurther preferably 2 or more. Further, the upper limit of the mass ratioof triethylene glycol alkyl ether to polyoxyalkylene alkyl ether is notparticularly limited, but is preferably 10 or less. When the mass ratioof triethylene glycol alkyl ether to polyoxyalkylene alkyl ether iswithin the above range, in the ink jet head nozzles, the ejection defectcaused by the separation of the surfactant tends to be furthersuppressed.

pH Adjuster

The ink composition according to the present embodiment may contain a pHadjuster. The pH adjuster can be used to facilitate the adjustment ofthe pH value of ink. The pH adjuster is not particularly limited, butexamples thereof include inorganic acids (for example, sulfuric acid,hydrochloric acid, and nitric acid), inorganic bases (for example,lithium hydroxide, sodium hydroxide, potassium hydroxide, and ammonia),organic bases (for example, triethanolamine, diethanolamine,monoethanolamine, and tripropanolamine), and organic acids (for example,adipic acid, citric acid, and succinic acid). These pH adjusters may beused alone or in combination of two or more kinds thereof.

Other Components

The ink composition according to the present embodiment may containvarious kinds of additives, such as a dissolution aid, a viscositymodifier, a pH adjuster, an antioxidant, a preservative, an antifungalagent, a corrosion inhibitor, and a chelating agent for capturing metalions influencing dispersion, for the purpose of maintaining the storagestability of the ink composition and the ejection stability of the inkcomposition from a head, preventing the clogging of a nozzle, andpreventing the degradation of the ink.

Dynamic Contact Angle

The dynamic contact angle of the ink composition of the presentembodiment to a silicon wafer at 100 msec after dropping is 24° orlower, preferably 22° or lower, and more preferably 20° or lower.Further, the dynamic contact angle of the ink composition of the presentembodiment to the silicon wafer at 5,100 msec after dropping is 9° orlower, preferably 7° or lower, and more preferably 5° or lower. When thedynamic contact angle of the ink composition to the silicon wafer iswithin the above range, the filling properties of an ink jet printer isfurther improved. The dynamic contact angle can be measured by themethods described in Examples.

EXAMPLES

The invention will be described in more detail with reference toExamples and Comparative Examples. The invention is not limited to thefollowing examples.

Materials for Ink Composition

The main materials for the ink composition used in the followingexamples and comparative examples are as follows.

Dye

Dye (Y-1-1): refer to below

Dye (Y-2-1): C.I. Direct Yellow 86

Dye (Y-2-2): C.I. Direct Yellow 132

Dye (Y-2-3): C.I. Direct Yellow 142

Dye (Y-3-1): refer to below

Surfactant

Olfine E1010 (the number of carbon atoms in the main chain: 10, theaddition number of moles of ethylene oxide: 10, HLB: 13 to 14,manufactured by Nissin Chemical Industry Co., Ltd.)

Surfynol 465 (the carbon number of main chain: 10, the addition numberof moles of ethylene oxide: 10, HLB: 9, manufactured by Air Products andChemicals, Inc.)

Surfynol 104PG50 (the carbon number of main chain: 10, no ethylene oxideadduct, HLB: 4, manufactured by Air Products and Chemicals, Inc.)

Newcol 1006 (polyoxyalkylene alkyl ether, manufactured by NipponNyukazai Co., Ltd.)

Solvent

dipropylene glycol-n-propyl ether

triethylene glycol monobutyl ether

glycerin

triethylene glycol

pH Adjuster

triethanolamine

Preparation of Ink Composition

Each material was mixed in the composition shown in Table below, andsufficiently stirred to obtain each ink composition. In Table below, theunit of numerical values is mass %, and the total is 100.0 mass %.

Dynamic Contact Angle

0.5 μL of the ink composition was dropped onto a silicon wafer, and thecontact angle of the ink composition was measured after 100 msec and5,100 msec from the time the ink composition was adhered to the siliconwafer. The contact angle thereof was measured using the PCA-1manufactured by Kyowa Interface Science Co., Ltd. The measurement of thecontact angle was performed under conditions of a temperature of 25° C.and a humidity of 50%. Meanwhile, ion exchange water was measured underthe measurement condition of dynamic surface tension the same as themeasurement condition of ink. As a result, the value of the contactangle of the water to the silicon wafer was 77° at 100 msec, and 75° at5,100 msec.

TABLE Examples Comparative Examples 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8Dye Dye (Y-1) 3.2 3.2 2.4 4.5 2.4 2.4 2.4 3.2 2.4 2.0 4.0 2.4 2.4 2.4Dye (Y-2-1): C.I. 0.8 0.6 0.5 0.6 0.6 0.8 0.6 4.0 2.0 0.6 0.6 0.6 DirectYellow 86 Dye (Y-2-2): C.I. 0.8 4.0 Direct Yellow 132 Dye (Y-2-3): C.I.0.6 Direct Yellow 142 Dye (Y-3) 0.5 1.5 1.5 1.0 4.0 1.0 1.0 1.0Surfactant Olfine E1010 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.30.3 0.3 0.3 Surfynol 465 4.0 Surfynol 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.30.3 0.3 0.3 0.3 0.3 0.3 0.3 104PG50 Newcol 1006 3.0 3.0 3.0 3.0 3.0 3.03.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Solvent Triethylene glycol 7.0 7.07.0 7.0 7.0 7.0 7.0 3.0 4.0 7.0 7.0 7.0 7.0 7.0 7.0 7.0 18.0 monobutylether Glycerin 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.010.0 10.0 10.0 10.0 10.0 10.0 Triethylene 10.0 10.0 10.0 10.0 10.0 10.010.0 14.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 glycol pHadjuster Triethanolamine 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.50.5 0.5 0.5 0.5 0.5 Water balance balance balance balance balancebalance balance balance balance balance balance balance balance balancebalance balance balance Total 100 100 100 100 100 100 100 100.0 100 100100 100 100 100 100 100 100 Dynamic contact Silicon wafer, 22 22 22 2222 22 22 22 22 22 22 22 22 22 27 25 27 angle 100 msec after droppingSilicon wafer, 7 7 7 7 7 7 7 7 7 7 7 7 7 7 13 10 13 5100 msec afterdropping Evaluation results (Intermittent) printing A A A A A A A B B AA A C C A A A stability Light resistance B B B B A A B B A C C C B A A AA Initial filling A A A A A A A B A A A A A A C C C properties

Light Resistance

The ink jet printer EP-805A (manufactured by Seiko Epson Corp.) wasfilled with the ink composition. A solid image adjusted such that ODvalues are 0.5, 1.0, 1.5, and 2.0 was printed on photo paper <gloss>(manufactured by Seiko Epson Corp.), thereby creating records,respectively.

The OD value (DO) of the obtained record was measured using a reflectiondensitometer (trade name: Spectrolino, manufactured by Gretag Inc.).Thereafter, the record was exposed using a xenon weather meter (tradename: XL75S, manufactured by Suga Test Instruments Co., Ltd.) for 6days, 12 days, and 18 days under conditions of a temperature of 23° C.,a relative humidity (RH) of 50%, and an illuminance of 75 klux. Afterthe exposure, the OD value (D) of the exposed record was measured usinga reflection densitometer (trade name: Spectrolino, manufactured byGretag Inc.), optical density residual rate (ROD) was obtained by thefollowing equation, and light resistance was evaluated according to thefollowing criteria.

ROD(%)=(D/D0)×100

Measurement condition: no light source filter, light source: D50,viewing angle: 2°

Evaluation Criteria

A: ROD of all records is 70% or more even after exposure for 18 days.

B: ROD of all records is 70% or more even after exposure for 12 days,but ROD is less than 70% after exposure for 18 days.

C: ROD of all records is 70% or more even after exposure for 6 days, butROD is less than 70% after exposure for 12 days.

D: ROD of all records is less than 70% after exposure for 6 days.

Initial Filling Properties

The ink cartridge of ink jet printer EP-805A (manufactured by SeikoEpson Corp.) was filled with each of the prepared ink sets. The initialfilling operation to a head was carried out according to the initialfilling sequence established by the EP-805A. Thereafter, nozzle checkingwas carried out in order to confirm whether ink can be discharged fromall the nozzles of the head. When nozzles unable to discharge ink exist,head cleaning (suction of ink in the nozzle) was carried out, and thenthe nozzle checking was carried out again. Based on the number of timesof cleaning required to discharge ink from all the nozzles, initialfilling properties were evaluated according to the following evaluationcriteria.

Evaluation Criteria

A: ink is discharged from all the nozzles by only the initial fillingsequence.

B: the number of times of cleaning required to discharge ink from allthe nozzles is one time.

C: the number of times of cleaning required to discharge ink from allthe nozzles is two or more times.

(Intermittent) Printing Stability

After whether the ink can be discharged from all the nozzles wasconfirmed according to the above “evaluation of initial fillingproperties”, a vertical rule line pattern was printed in parallel to thepaper feed direction of the ink jet printer using a head operationsequence program for evaluation, and (intermittent) printing stabilitywas evaluated according to the following evaluation criteria.

Test environment: Rh of 25% at 40° C.

Head operation sequence for evaluation: the head was reciprocated for 40seconds in a head main scanning direction in a state in which the inkwas not discharged, and then ink blanking (flushing) was repeated fivetimes, and then two rule lines were printed.

Evaluation Criteria

A: Rule lines are normally printed both first time and second time(visual observation).

B: Rule lines are normally printed first time or second time (visualobservation).

C: Rule lines are not normally printed both first time and second time(visual observation).

The entire disclosure of Japanese Patent Application No. 2014-225371,filed Nov. 5, 2014 is expressly incorporated by reference herein.

What is claimed is:
 1. An ink composition, comprising: a dye (Y-1)represented by a formula below; and a dye (Y-2) selected from the groupconsisting of C.I. Direct Yellows 86, 132, and 142, wherein the contentratio A of the dye (Y-1) and the dye (Y-2) (the dye (Y-1):the dye (Y-2))is 7:3 to 9.5:0.5, the content of the dye (Y-1) is 2.0 mass % to 5.0mass %, and the dynamic contact angle of the composition to a siliconwafer is 24° or lower at 100 msec after dropping, and is 9° or lower at5,100 msec after dropping,

(in Formula (Y-1), R₄ represents a substituent, R₅ represents —OR₆ or—NHR₇, each of R₆ and R₇ represents a hydrogen atom or a substituent, X₃represents a divalent linking group, n0 is 0 or 1, Ar₃ represents adivalent heterocyclic group, and Ar₄ represents an alkyl group, an arylgroup, or a triazine group).
 2. The ink composition according to claim1, wherein the content of the dye (Y-2) is 0.10 mass % to 1.0 mass %. 3.The ink composition according to claim 1, comprising a dye (Y-3)represented by a formula below, wherein the content of the dye (Y-3) is0.50 mass % to 1.5 mass %,

(in Formula (Y-3), R₁₃'s each independently represent a hydrogen atom ora substituent, R₁₄'s each independently represent —OR₁₆, —NHR₁₇, or acyano group, each of R₁₆ and R₁₇ represents a hydrogen atom or asubstituent, X₁ represents a substituted or unsubstituted aryl group ora substituted or unsubstituted triazine group, n6 is 0 or 1, Ar₁'s eachindependently represent a divalent heterocyclic group, and Ar₂'s eachindependently represent a substituted or unsubstituted alkyl group, asubstituted or unsubstituted aryl group, or a substituted orunsubstituted triazine group).
 4. The ink composition according to claim1, comprising: an alkylene oxide adduct of an acetylene glycol having amain chain of 12 or more carbon atoms; and an acetylene glycol having amain chain of 10 or more carbon atoms.
 5. The ink composition accordingto claim 1, comprising polyoxyalkylene alkyl ether.
 6. The inkcomposition according to claim 1, comprising triethylene glycol alkylether.
 7. The ink composition according to claim 6, wherein the massratio of the triethylene glycol alkyl ether to the polyoxyalkylene alkylether is 2 or more.
 8. The ink composition according to claim 5, whereinthe content of the polyoxyalkylene alkyl ether is 1.0 mass % to 5.0 mass%.
 9. The ink composition according to claim 6, wherein the content ofthe triethylene glycol alkyl ether is 3.0 mass % to 15 mass %.
 10. Theink composition according to claim 6, wherein the triethylene glycolalkyl ether includes triethylene glycol monobutyl ether.